The enthalpies of solution of K2Sr[B4O5(OH)(4)](21)center dot 10H(2)O(cr) in approximately 1 mol dm(-1) aqueous hydrochloric acid and of SrCl2 center dot 6H(2)O(cr) in aqueous solution (hydrochloric acid + boric acid + potassium chloride) were measured by solution calorimetry. From these results and other data, the standard molar enthalpy of formation Delta H-f(m)o of K2Sr[B4O5(OH)4](2)center dot 10H(2)O(cr) has been derived to be -(10904.47 +/- 6.46) U mol(-1) at 298.15 K. According to a group contribution method, the standard molar Gibbs free energy Delta(f)G(m)(o). and the standard molar entropy S-m(o) of (KSr)-Sr-2[B4O5(OH)(4)](2)center dot 10H(2)O(cr) were also calculated to be -9690.78 U mol(-1) and 858.31 J K-1 mol-1 at 298.15 K. (c) 2007 Elsevier B.V. All rights reserved.